Apparatus and method for controlling hydrogen concentration for a fuel cell system

Abstract

A hydrogen concentration control device for a fuel cell system having a hydrogen supply system for supplying hydrogen to an anode of a fuel cell, the device comprising: a sensor (13) for measuring the hydrogen concentration, which is arranged directly in a hydrogen tank (5) of the hydrogen supply system or in a hydrogen supply pipe connected between the hydrogen tank (5) and the anode; and a controller (4) provided for calculating the hydrogen concentration in the anode channel based on the hydrogen concentration measured by the sensor (13) for measuring the hydrogen concentration in the hydrogen tank (5) and a transitional amount of impurities and performing purge control of gases in the anode channel by opening a hydrogen purge valve (12) when the controller (4) determines that the calculated hydrogen concentration in the anode channel has fallen below a reference value, wherein the transitional amount of impurities includes amounts of oxygen and nitrogen transferred from the cathode to the anode.

Description

BACKGROUND(a) Technical field

[0001] The present invention relates to a hydrogen concentration control apparatus and method for a fuel cell system. More specifically, the present invention relates to a hydrogen concentration control apparatus and method for a fuel cell system, which are adapted to maintain the hydrogen concentration of an anode in a fuel cell system at an appropriate level according to the concentration of hydrogen supplied to the fuel cell of the fuel cell system. (b) Background of the invention

[0002] A fuel cell system typically includes a hydrogen supply system and an oxygen supply system for supplying reactant gases (hydrogen and atmospheric oxygen); a fuel cell stack for electrochemically converting chemical energy obtained from an oxidation and reduction reaction of the reactant gases into electrical energy to generate heat as a reaction product and electrical energy; and a water and thermal management system for cooling the fuel cell stack.

[0003] Among these components of the fuel cell system, the fuel cell stack for practical electricity generation has a stacked structure of unit cells in the two to three-digit range, each of which consists of a membrane electrode assembly (MEA) (which may also be referred to as an electrode-membrane assembly or electrode-membrane junction body) and a separator in which a pair of end plates are mounted at the opposite ends of the fuel cell stack to fix the individually stacked components to each other with a predetermined surface pressure and to carry out current collection.

[0004] The MEA includes a polymer electrolyte membrane, an anode, and a cathode arranged with the polymer electrolyte membrane sandwiched therebetween, wherein the anode (which may also be referred to as a hydrogen electrode, fuel electrode, negative electrode, or oxidation electrode) and the cathode (which may also be referred to as an air electrode, oxygen electrode, positive electrode, or reduction electrode) are formed by adsorbing a catalytic layer containing nanoparticles of catalysts onto a reinforcing layer.

[0005] The electricity generation principle of such a fuel cell system will now be briefly described. As hydrogen is supplied to the anode of the fuel cell stack, an oxidation reaction of the hydrogen is initiated at the anode, thereby generating hydrogen ions (protons) and electrons. The resulting hydrogen ions and electrons are moved to the cathode through an electrolyte membrane and a separator. Water is then generated at the cathode through an electrochemical reaction between the hydrogen ions and electrons moved by the anode and atmospheric oxygen. The electrical energy ultimately generated from the circulation of such electrons is applied through a current collector of the end plates to a load requiring the electrical energy (e.g., a motor for driving a fuel cell vehicle).

[0006] Meanwhile, a conventional hydrogen concentration control technique for maintaining the hydrogen concentration of the anode of a fuel cell stack at an appropriate level by measuring the concentration of hydrogen supplied to the anode is applied to various conventional hydrogen supply systems for supplying hydrogen using a modifier. For example, the conventional control technique confirms and controls the concentration of hydrogen generated by such a modifier and the impurity content in the hydrogen so that hydrogen is supplied at a concentration equal to or higher than a reference concentration. When impurities harmful to the catalytic layer are contained in the hydrogen, the driving of the hydrogen supply system is stopped.

[0007] Furthermore, another conventional hydrogen concentration control technique is applied to a hydrogen supply system. The conventional hydrogen concentration control technique measures the impedance of a fuel cell stack to determine the hydrogen concentration in the anode channel of the fuel cell based on the measured impedance. When the hydrogen concentration is lower than a reference value, the conventional hydrogen control technique maintains the hydrogen concentration by purging control of the anode. However, there is a difficulty in accurately measuring the hydrogen concentration by measuring the impedance of a fuel cell vehicle whose fuel cell practically suffers from a continuous fluctuation in current load. In particular, there is a problem that the fuel cell should necessarily be equipped with an expensive impedance measuring device.

[0008] Yet another conventional technique is employed, in which the conventional technique provides a sensor for measuring the hydrogen concentration in either a hydrogen return pipe or an outlet end of an anode of a fuel cell stack to confirm the concentrations of hydrogen and anode impurities. This technique confirms the performance status of all unit cells of the fuel cell stack. If the performance is lower than a reference value due to excessive impurities in the corresponding unit cell, the conventional technique performs a hydrogen purge to remove the impurities.

[0009] However, in this embodiment, when confirming the hydrogen concentration on the return pipe side, there is a difficulty in practically applying the conventional technique because the returned hydrogen amount is not constant according to the operating conditions of the fuel cell, and it is very difficult to accurately measure the hydrogen concentration under the influence of condensate. Furthermore, there is a sufficiently high possibility that damage to the anode and a reduction in durability may still occur with this technique because the hydrogen purge process is often performed after the problem has already occurred.In addition, since there is indeed a large amount of condensed water at the outlet end of the fuel cell anode, which makes normal operation of the sensor for measuring the hydrogen concentration at the outlet end difficult, and since the possibility of measurement error or failure of the sensor caused by the water is very high, it is difficult to apply this conventional technology to a current product.

[0010] Yet another conventional technique is used. The conventional technique provides a sensor for measuring the hydrogen concentration in a hydrogen return pipe to confirm the impurity concentration in an anode channel, and then performs hydrogen purge control based on this confirmation. However, since a large amount of condensate exists in the return pipe, it is difficult to measure the hydrogen concentration in most cases. Furthermore, it is again very likely that the above-mentioned process will be performed after an electrode of the fuel cell has already been damaged due to impurities in the anode, and consequently, the durability of the anode will be severely compromised.

[0011] Incidentally, US 2007 / 0 243 437 A1 discloses a fuel cell system comprising pressure recovery means for recovering the pressure in a hydrogen system of a fuel cell and pressure estimation means for estimating the hydrogen partial pressure in the hydrogen system. Furthermore, the fuel cell system includes a means for estimating the impurity concentration in the hydrogen system. That is, the means for estimating the impurity concentration estimates the impurity concentration taking into account the current state of the hydrogen system. Thus, the means for estimating the impurity concentration accurately estimates the impurity concentration in the hydrogen system of the fuel cell.

[0012] In order to improve the fuel efficiency of a fuel cell system by reducing the frequency of performing the anode cleaning gas purge, JP 2010 - 287 320 A discloses the fuel cell system in question, comprising a fuel cell stack that generates electricity by electrochemical reaction of fuel gas supplied to a fuel electrode with atmospheric oxygen supplied to an air electrode 1b, a circulation path and a circulation means for circulating exhaust hydrogen discharged from the fuel electrode of the fuel cell stack to the fuel electrode, a purge valve that discharges exhaust hydrogen from an anode system to the outside, a supply line for supplying fuel gas to the fuel electrode and to the circulation line, a purge valve control device for controlling an opening degree of the purge valve,a nitrogen partial pressure detection device for detecting the nitrogen partial pressure in the fuel gas supplied to the fuel electrode, and an air electrode nitrogen partial pressure detection means for detecting the nitrogen partial pressure in the air supplied to the air electrode. In an operating range where the nitrogen partial pressure in the air is required to be equal to or greater than the nitrogen pressure in the fuel gas, the purge valve control device opens the vent valve. SUMMARY OF REVELATION

[0013] The present invention provides a hydrogen concentration control apparatus and method for a fuel cell system, wherein a sensor for measuring the hydrogen concentration is directly provided in a hydrogen storage device (e.g., a hydrogen tank), the hydrogen concentration in the hydrogen tank and the impurity concentration in an anode channel of the fuel cell system are calculated based on the measured hydrogen concentration, and when it is determined that the hydrogen concentration in the anode channel decreases below a reference value with which the fuel cell system can be stably operated, purge control is performed for discharging the gases (hydrogen and impurities) in the anode channel to the outside such that the hydrogen concentration in the anode channel of the fuel cell system can be maintained not less than the reference value.

[0014] In one aspect, the present invention provides a hydrogen concentration control device for a fuel cell system having a hydrogen supply system for supplying hydrogen to an anode of a fuel cell. The exemplary hydrogen concentration control device includes a sensor for measuring hydrogen concentration, which is mounted directly in a hydrogen storage device (e.g., a hydrogen tank of the hydrogen supply system or a hydrogen supply pipe connected between the hydrogen tank and the anode), and a controller.The controller is configured to calculate the hydrogen concentration in the anode channel based on the hydrogen concentration measured by the hydrogen concentration sensor, and to perform purge control for the gases in the anode channel by opening a hydrogen purge valve when it is determined that the calculated hydrogen concentration has decreased below a reference value. The transfer amount of impurities includes amounts of oxygen and nitrogen transferred from the cathode to the anode.

[0015] In another aspect, the present invention provides a method for controlling the hydrogen concentration of a fuel cell system, which includes: measuring the hydrogen concentration in a hydrogen tank or hydrogen supply pipe; calculating a change in the hydrogen concentration in the anode channel and impurity concentration based on the measured hydrogen concentration; and performing hydrogen purging by opening a hydrogen purge valve for a predetermined period of time when it is determined that the impurity concentration in the anode channel is not less than an upper limit of the reference value (β) to allow hydrogen and impurities to be discharged to the outside, wherein the transfer amount of impurities (impurity concentration) includes amounts of oxygen and nitrogen transferred from the cathode to the anode.

[0016] By virtue of the above-mentioned features, the present invention provides the following effects.

[0017] According to the present invention, a sensor for measuring hydrogen concentration is directly provided at a specific position in a hydrogen tank or a hydrogen supply pipe. The hydrogen concentration and impurity concentration in the anode channel of the fuel cell system are calculated based on the measured hydrogen concentration. When it is determined that the hydrogen concentration in the anode channel drops below a reference hydrogen value at which the fuel cell system can operate stably, purge control is performed. In other words, when it is determined that the impurity concentration has increased beyond a predetermined reference value, purge control is performed to discharge the gases (hydrogen and impurities) in the anode channel to the outside.Consequently, the hydrogen concentration in the anode channel of the fuel cell system can be maintained at or higher than the reference value for hydrogen.

[0018] Furthermore, regardless of the concentration of hydrogen charged in the hydrogen tank, purge control is performed to maintain the hydrogen concentration in the anode channel at an appropriate level by calculating the hydrogen concentration and impurity concentration in the anode channel based on the hydrogen concentration measured by the hydrogen concentration sensor provided in the hydrogen tank. That is, even if hydrogen is charged with different concentrations from one regional hydrogen refueling station to another, purge control is performed. Consequently, it is possible to ensure the stable operation of the fuel cell system and prevent damage to the anode and a reduction in its durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above-mentioned and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof, which are illustrated in the accompanying drawings, which are given below for illustrative purposes only and thus do not limit the present invention, and in which: the Fig. 1 and Fig. 2 are schematic views each showing a construction of the hydrogen concentration control apparatus for a fuel cell system of the exemplary embodiment of the present invention; Fig. 3 is a schematic view for describing how movements of substances are implemented in relation to an anode channel of a fuel cell of the exemplary embodiment of the present invention; Fig. 4 is a flowchart for describing the inventive method for controlling hydrogen concentration for a fuel cell system of the exemplary embodiment of the present invention; and Fig. 5 is a graph showing hydrogen purge cycles performed in the anode channel according to the exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below.

[0021] It should be understood that the term “vehicle” or “vehicular” or other similar term used herein includes motor vehicles in general, such as passenger cars, which include off-road vehicles (SUVs), buses, trucks, various business cars, watercraft, which include a variety of boats and vessels, aircraft, and the like, and includes hybrid vehicles, electric vehicles, internal combustion, plug-in electric hybrid vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from raw materials other than petroleum).

[0022] It is well understood that the performance of a polymer electrolyte fuel cell system is directly affected by the concentration of hydrogen supplied to the anode of the fuel cell system. When the purity of the supplied hydrogen is low, the voltage obtained at the same current on a current-voltage characteristic curve is also low. Furthermore, when the concentration is reduced below a predetermined level, the hydrogen becomes thin at the channel outlet end of the anode, causing a rapid voltage drop of the fuel cell due to the loss of hydrogen concentration.

[0023] Since the hydrogen concentrations of all regional hydrogen refueling stations cannot be the same, it is particularly necessary to develop a control technology that can stably maintain the performance of a fuel cell according to the concentration of hydrogen supplied to an anode of a fuel cell stack.

[0024] To this end, the present invention emphasizes making it possible to maintain the hydrogen concentration in the anode channel of the fuel cell system at a level equal to or higher than a reference value required for stable operation of the fuel cell system by calculating the hydrogen concentration in the anode channel according to an operation state of the fuel cell based on the hydrogen concentration measured when a device capable of measuring the hydrogen concentration is provided in a refillable hydrogen storage tank (also: hydrogen storage device, with the same reference numeral) or a hydrogen supply pipe, and by performing purge control for discharging the gas (hydrogen and impurities) inside the anode to the outside when it is determined that the hydrogen concentration in the anode channel is reduced below the reference value.

[0025] Fig. 1 is a schematic view showing a structure of the hydrogen concentration control apparatus for a fuel cell system of an exemplary embodiment of the present invention, a hydrogen supply system for supplying hydrogen to an anode of a fuel cell stack, and a hydrogen return system for returning the hydrogen to the anode. Specifically, a current sensor 2 and a voltage sensor 3 are provided for measuring the current and voltage of the electricity generated by the fuel cell stack, respectively.

[0026] Regarding the step-by-step construction and operation of the hydrogen supply device, the concentration is controlled by: (1) discharging the hydrogen into a hydrogen tank 5 while regulating the hydrogen to a predetermined pressure by a high-pressure regulator 6; (2) allowing the discharged hydrogen to flow through a solenoid valve 7, which is in the open state while the fuel cell system is operated; (3) re-regulating the hydrogen that has passed through the solenoid valve 7 to a predetermined pressure by a low-pressure regulator 8; and (4) supplying the hydrogen that has passed through the low-pressure regulator 8 to the anode of the fuel cell stack 1, wherein the flow rate of the hydrogen supplied to the anode is measured by a flow meter 9.

[0027] The hydrogen thus supplied to the anode of the fuel cell stack reacts with atmospheric oxygen to generate electricity, and then a part of the unreacted hydrogen is returned to an inlet side of the anode through a solenoid valve 10, e.g., a hydrogen recirculation valve, by driving a hydrogen circulating fan 11 of the hydrogen recirculation system, and the rest of the unreacted hydrogen is discharged to the outside through a solenoid valve 12, e.g., a hydrogen purge valve.

[0028] Advantageously, the present invention enables stable operation of the fuel cell system despite fluctuations in the concentration of hydrogen supplied from the hydrogen tank 5 by variably controlling the amount of discharged hydrogen and impurities according to the hydrogen concentration in the hydrogen storage device 5 when the hydrogen stored in the hydrogen storage device 5 is supplied to the anode channel through the hydrogen supply pipe.

[0029] The concentration of hydrogen charged in the hydrogen storage device 5 varies each time hydrogen is charged, since regional hydrogen refueling stations have different hydrogen concentrations. Unless the fluctuation in the concentration of hydrogen charged in the hydrogen storage device 5 is taken into account, the concentration of hydrogen supplied from the hydrogen tank to the anode of the stack 1 will also vary, causing the performance of the fuel cells to sometimes be adversely affected.

[0030] That is, if the hydrogen concentration in the hydrogen tank 5 is too low, the voltage of the fuel cell will drop abruptly, which may cause damage to the anode electrode due to reverse voltage. Electrode damage may degrade the performance of the fuel cell and cause problems with durability and longevity.

[0031] In order to solve the above-mentioned problems, in the present invention, a sensor 13 for measuring the hydrogen concentration is directly mounted at a predetermined position in the hydrogen storage device 5 (e.g., a hydrogen tank or the hydrogen supply pipe), the hydrogen concentration in the anode channel is calculated based on the hydrogen concentration in the hydrogen tank 5 measured by the sensor 13 for measuring the hydrogen concentration, and the gases (e.g., hydrogen and impurities) in the anode are discharged to the outside by purge control when it is determined that the hydrogen concentration in the anode channel is reduced below a reference value for hydrogen with which the fuel cell system can be stably operated.Consequently, when it is determined that the concentration of impurities is higher than a reference value for impurities, these gases in the anode channel are discharged so that the hydrogen concentration in the anode channel can be kept equal to or higher than the reference value for hydrogen and the impurity concentration can be kept below the reference value for impurities.

[0032] According to another embodiment of the present invention, no sensor for measuring the hydrogen concentration is provided in the hydrogen storage device. In such a case, the concentration of the hydrogen charged in the hydrogen storage device will not change unless new hydrogen is charged again. Therefore, when new hydrogen is charged from a hydrogen refueling station, the controller can receive information concerning the concentration and charged amount of the new hydrogen directly from the hydrogen refueling station through a wired or wireless communication device and calculate the actual hydrogen concentration in the hydrogen storage device together with information concerning the amount and concentration of hydrogen remaining in the hydrogen storage device before the new hydrogen is charged into the system.

[0033] After the hydrogen concentration is measured by the sensor for measuring the hydrogen concentration provided in the hydrogen storage device (ie, a hydrogen tank or hydrogen supply pipe), or the actual hydrogen concentration in the hydrogen is measured using the information directly obtained from a hydrogen refueling station and concerning the concentration and charged amount of hydrogen, the change in the hydrogen concentration in the anode channel of the fuel cell system and the impurity concentration are calculated based on the measured hydrogen concentration.

[0034] Now, the calculation of the change of hydrogen concentration in the anode channel of the fuel cell system and the impurity concentration in the same will be described in more detail.

[0035] To calculate the change of the hydrogen concentration in the anode channel and the impurity concentration therein during the operation of the fuel cell system, the entire anode channel should preferably be set as a single control volume.

[0036] Fig. Figure 3 shows conduction fluxes of individual substances flowing between the inside and outside of the anode channel, which is set as the only control volume. As in Fig. As shown in Figure 3, hydrogen is consumed in the anode by an electrochemical reaction, whereby the hydrogen (ṁ H2,in ) and the impurities (ṁ im ) from the hydrogen storage device 5 by the consumed amount of hydrogen (ṁ H2,ra ) to the anode.

[0037] Since a transition occurs through a membrane electrode assembly (MEA) due to the difference in concentration between the gases supplied to the anode and cathode during the operation of the fuel cell system, oxygen (ṁ O2,CO ) and nitrogen (ṁ N2,CO ) from the cathode to the anode and hydrogen (ṁ H2,CO ) from the anode to the cathode.

[0038] Based on these supplied amounts and transition amounts of the individual substances flowing between the inside and outside of the anode channel, which is set as the only control volume, the impurity concentration (C im ) in the anode channel, which changes with time, can be expressed below as Equation 1. Cim=mim,an+∫(m˙im+m˙O2,co+m˙N2,co)dtmH2,an+mim,an+∫(m˙H2in+m˙im−m˙H2.ra+m˙O2.co+m˙N2.co−m˙H2.co)dt

[0039] In equation 1, m H2,an and m im,anthe initial amounts of hydrogen or impurities in the anode channel, where the impurity concentration means a molar concentration and the amount of each substance means the number of moles.

[0040] Assuming that there is no pressure change in the control volume, the sum of the amount of hydrogen (ṁ H2,in ) and the amount of impurities (ṁ im ), which is fed to the inlet of the anode, is equal to the sum of the amount of hydrogen consumed by the electrochemical reaction (ṁ H2,ra ) and the transition amounts of substances flowing through the MEA. However, since the transition amounts are very small, the term for the transition amounts can be ignored. Assuming that there is no pressure change in the control volume, the sum of the amount of hydrogen (ṁ H2,in ) and the amount of impurities (ṁ im) supplied to the inlet of the anode is essentially equal to the amount of hydrogen consumed by the electrochemical reaction (ṁ H2,ra ).

[0041] To simplify Equation 1, the sum of the amounts of oxygen and nitrogen moved due to the transition can be expressed below as Equation 2. m˙im,co=m˙O2,co+m˙N2,co

[0042] The amount of hydrogen consumed by the electrochemical reaction (ṁ H2,ra ), since it is proportional to the consumed current of the fuel cell (i), can be expressed below as equation 3. m˙H2,ra=Ai

[0043] Furthermore, assuming that the impurity concentration in the hydrogen storage device is α, the amounts of impurities and hydrogen supplied to the anode can be expressed as Equations 4 and 5 below. m˙H2,in=(1−α)Ai m˙im=αAi

[0044] Therefore, when Equations 2 to 5 are substituted into Equation 1, Equation 1 can be simplified to calculate the impurity concentration in the anode channel and expressed as Equation 6 below. Cim=mim,an+αA∫idt+∫m˙im,codtmH2,am+mim,an

[0045] According to the present invention, the impurity concentration (C im ) in the anode channel according to the impurity concentration (α) in the hydrogen storage device 5 using Equation 6, and when it is determined that the impurity concentration (C im) is equal to or higher than an upper limit value of the reference concentration (β) previously obtained by a test or the like, the hydrogen purge valve 12 is opened for a predetermined period of time to perform hydrogen purge such that the impurities can be discharged.

[0046] Preferably, the hydrogen purge valve 12 is opened (via an electronic control) such that the impurities can be discharged until the impurity concentration in the anode channel is reduced below a lower limit of the reference concentration (ε), and when it is determined that the impurity concentration in the anode channel is reduced below the lower limit of the reference concentration (ε), the hydrogen purge valve 12 is closed to terminate the hydrogen purge.

[0047] Although the above exemplary embodiment is described as using a single controller to perform the above process, it should be understood that the above processes may also be performed by a plurality of controllers or control units.

[0048] The control logic of the present invention may also be embodied as a non-transitory, computer-readable medium on a computer-readable storage medium containing executable program instructions executed by a processor, controller, or the like. Examples of computer-readable storage media include read-only memory, random access memory, compact disc read-only memory (CD-ROMs), magnetic tape, floppy disks, memory sticks, smart cards, and optical data storage devices. The computer-readable recording medium may also be distributed in network-coupled computer systems such that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0049] Meanwhile, since the increase of the impurity concentration in the anode channel with time is proportional to the impurity concentration in the hydrogen storage device, the impurity concentration in the anode channel increases rapidly with time when the impurity concentration in the hydrogen storage device is high. As shown in Fig. 5, it is therefore desirable to increase the hydrogen purge cycles in proportion to the impurity concentration in the hydrogen storage device 5.

[0050] Thus, by directly providing a sensor for measuring the hydrogen concentration at a specific position in the hydrogen storage device (e.g., the hydrogen tank or the hydrogen supply pipe), calculating the hydrogen concentration in the anode channel based on the hydrogen concentration in the hydrogen storage device measured by the sensor for measuring the hydrogen concentration, and discharging the gases (hydrogen and impurities) in the anode to the outside by purge control when it is determined that the hydrogen concentration in the anode channel is reduced below a reference value for hydrogen with which the fuel cell system can be stably operated, the hydrogen concentration in the anode channel can be maintained at a level equal to or higher than the reference value for hydrogen and the impurity concentration can be maintained below the reference value for impurities.Consequently, it is possible to ensure the stable operation of the fuel cell system.

[0051] The invention has been described in detail with reference to exemplary embodiments thereof. However, it will be appreciated by one of skill in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and equivalents thereof.

Claims

[1] A hydrogen concentration control device for a fuel cell system having a hydrogen supply system for supplying hydrogen to an anode of a fuel cell, the device comprising: a sensor (13) for measuring the hydrogen concentration, which is arranged directly in a hydrogen tank (5) of the hydrogen supply system or in a hydrogen supply pipe connected between the hydrogen tank (5) and the anode; and a controller (4) provided for calculating the hydrogen concentration in the anode channel based on the hydrogen concentration measured by the sensor (13) for measuring the hydrogen concentration in the hydrogen tank (5) and a transitional amount of impurities and performing purge control of gases in the anode channel by opening a hydrogen purge valve (12) when the controller (4) determines that the calculated hydrogen concentration in the anode channel has fallen below a reference value, wherein the transitional amount of impurities includes amounts of oxygen and nitrogen transferred from the cathode to the anode. [2] A hydrogen concentration control device for a fuel cell system having a hydrogen supply system for supplying hydrogen to an anode of a fuel cell, the device comprising: a controller (4) provided for calculating a hydrogen concentration in the anode channel and for performing purge control of gases in the anode channel by opening a hydrogen purge valve (12) when the controller (4) determines that the calculated hydrogen concentration has fallen below a reference value; and a wired or wireless communication device for transmitting information relating to the concentration and quantity of hydrogen charged from a hydrogen refuelling station; wherein the controller (4) determines a hydrogen concentration in the hydrogen tank (5) based on the information regarding the concentration and the amount of charged hydrogen available from the wired or wireless communication device, and then determines the hydrogen concentration in the anode channel based on the hydrogen concentration in the hydrogen tank (5). [3] A method for controlling the hydrogen concentration for a fuel cell system, the method comprising: Measuring a hydrogen concentration in a hydrogen tank (5) or a hydrogen supply pipe by a sensor (13); Calculating a change in the hydrogen concentration in the anode channel and impurity concentration therein based on the measured hydrogen concentration in the hydrogen tank (5) and a transition amount of impurities by a controller (4); Determining by the controller (4) whether the calculated hydrogen concentration in the anode channel has fallen below a predetermined reference value; and in response to determining that the hydrogen concentration in the anode channel has fallen below a predetermined reference value, performing a hydrogen purge by opening a valve (12) for a predetermined period of time so that hydrogen and impurities are discharged to the outside, wherein the transfer amount of impurities comprises amounts of oxygen and nitrogen transferred from the cathode to the anode. [4] The method of claim 3, wherein calculating the change in the hydrogen concentration in the anode channel and impurity concentration further comprises calculating the impurity concentration (C im ) according to the impurity concentration (α) using an equation given by Cim=mim,an+αA∫idt+∫m˙im,codtmH2,an+mim,an is defined, the equation being obtained by setting an entirety of the anode channel as a single control volume. [5] The method according to claim 3, wherein the hydrogen purging is performed until the impurity concentration in the anode channel is reduced below the lower limit of the reference value (ε), and when the impurity concentration in the anode channel is reduced below a lower limit of the reference value, the hydrogen purging valve (12) is closed to terminate the hydrogen purging. [6] The method according to claim 3, wherein when the impurity concentration in the hydrogen tank (5) or the hydrogen supply pipe is high, the hydrogen purge cycles are increased in proportion to the impurity concentration in the hydrogen tank (5) or the hydrogen supply pipe. [7] A device for controlling hydrogen concentration, the device comprising: a sensor (13) which is arranged directly in a hydrogen storage device of a hybrid vehicle and is provided to measure the concentration of hydrogen in a hydrogen storage device; and a controller (4) which is provided for calculating a hydrogen concentration in an anode channel of a fuel cell based on the hydrogen concentration in the hydrogen storage device measured by the sensor (13) and a transitional amount of impurities and for performing a purge control of gases in the anode channel by opening a valve (12) when the controller (4) calculates that the hydrogen concentration has fallen below a reference value, wherein the transfer amount of impurities comprises amounts of oxygen and nitrogen transferred from the cathode to the anode. [8] A hydrogen concentration control device according to claim 1, wherein the hydrogen concentration control device is installed in a vehicle. [9] A method for controlling the hydrogen concentration for a fuel cell system, comprising the following steps: Transmitting, by a wired or wireless communication device, information relating to a concentration and a quantity of hydrogen charged at a hydrogen refueling station; Calculating by a controller (4) a hydrogen concentration in the hydrogen tank (5) based on the information regarding the concentration and the charged amount of hydrogen obtained from the wired or wireless communication calibration device; Calculating by a controller (4) a change in the hydrogen concentration in the anode channel and an impurity concentration contained therein on the basis of the calculated hydrogen concentration in the hydrogen tank (5); and Determining by the controller (4) whether the estimated hydrogen concentration in the anode channel has fallen below a predetermined reference value; in response to determining that the hydrogen concentration in the anode channel has fallen below a predetermined reference value, performing a hydrogen purge by opening a valve for a predetermined period of time so that the hydrogen and the impurities are discharged to the outside, wherein the transfer amount of impurities comprises amounts of oxygen and nitrogen transferred from the cathode to the anode. [10] The method of claim 9, wherein calculating the changes in the hydrogen concentration in the anode channel and the impurity concentration to which calculating the impurity concentration (C im ) according to the impurity concentration (α) using an equation given by Cim=mim,an+αA∫idt+∫m˙im,codtmH2,an+mim,an is defined; the equation is obtained by setting an entirety of the anode channel as a single control volume. [11] The method according to claim 9, wherein the hydrogen purging is performed until the impurity concentration in the anode channel is reduced below the lower limit of the reference value (ε), and when the impurity concentration in the anode channel is reduced below a lower limit of the reference value, the hydrogen purging valve (12) is closed to terminate the hydrogen purging. [12] The method according to claim 9, wherein when the impurity concentration in the hydrogen tank (5) or the hydrogen supply pipe is high, the hydrogen purge cycles are increased in proportion to the impurity concentration in the hydrogen tank (5) or the hydrogen supply pipe.

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